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A.. L. WILKES HEAT ,`CONTROL FOB EtECTRIC FURNACES. Mfrucmou man Aua.2. me.

Patented May 10, 1921.

1 particularly i y'citizen of theUnitedStates,

UNIT

'ToQall whom t may concern;

Be it known that I, ALFRED L. Winans, a V residing at Los ,An es, in the co tyof Los Angeles', State ofialifornia,` have invented new and vuseful lmprovements in; HeatE Controls fon Electric Furnaces, ofwhichthe following isaspecilisation. i- 'I A Thsri'nvention-relates toheat control de- -vices or! electric urnaceag and particularly 1:0.,1 electric 1 furnaces. suchf as are Y.used 4.in

-.-. dentistry. 'It an Qbject offtheinventionjto provide 'a .device of this j character which .automatically .control the heating of an oven-and which will automatically turn the oven-:off when itreaches a predetermined he invention is particularly directed to provide-. fa-.fsimple and reliable mechanism Whichwvillre ate en -oven so as to heat gradually" ian substantially evenly. The gradual heating ofthe oven .causes articles which are in .theo'ven to heat or bake evenly 'andfthereby eliminates warping or cracking of saidarticles due to-sudden changes in temperature. This feature of the invention is desirable in connection with porcelain used in denor even baking.

'the invention is the by the heat of the dental ovens as the tstry requires gradual A'urther feature of controlling of theoven said'oveng'- that is, before the-control mechanism operates so as to cause an increase in the vtemperature of the oven, the oven must reach a certain redetermined temperature. The mechanism 1s so arranged that it can be set in such a manner as to cause the temperature of the oven to increase whensaid oven reaches -certain temperatures. The construction and arrangement of the mechanism-may 4be such as to cause further rise in temperature just as the oven reaches the maximum 'tempera-ture allowed by the previousactuation. When the mechanism is arranged in this manner the heating of the oven will be gradual and even.

Further objects of the inventionas well as the details of construction of a preferred form of the invention will be readily understood fromthe following detailed description in which reference is hadttol the -accompanying drawings, in whichv Figure 1 is a plan view of the oven; Fig. 2 is an enlarged detail section taken as indicated by line 2-2 on Fig. 1, showing the maincontrol switch; Fig. 3 is an enlarged detail section taken as indicated by line En STATES.;

an etended portion' lpivotallymounted at .contact-s 33,

PATENT' OFFICE.

, a .maar concmonron Etnea-raie FUnNaons.

specification@ tte-ri Patent. Patented May 10, 1921. animation mea augustV 2. 191.9.. '.seriarig'piias't" Il 5 A3-3 onFig. Fig. 4 islanlenlargdpln .view of the parts shoy'vizfiiilLFig.A 3'; di an enlar ed .detailfse'cti'rij tlienfsfindll- .catedby ine5--5 on Fi' .-1, showingaace :view' of the pyrometer; A fg. 6 is 'an enlarged detailedf section taken'as indicated byline the electrical system;

ance' which? is vcent'rcpllegl fcolnzrolling engages a contact 16; The bladefljisfpivotally mounted at .17V on a bracket 41 8 andhas asprng 20. The spring 20'isL connected between the poi-'tion 19 and they base 11' iand tends at' all times .to open the Switch.'4 The blade 15 is kept in engagement with the contact '16 by a hook portion'21 on theend of a lever arm 22. llhchook-21en`gages affpin 23 which projects from the blade 15. The lever arm 22 is one arm oiga lever 24 wlichis 25"-on a bracket 26. The lever arm- 27 ofl the lever 24;.extends downwardly and is .adapted to befm'ved by electro-'magnet 28. When the electrolina'gnet 2S is energized, as will hereinafter' beidescribed,'the lever arm 27 is' moved'in the direction indicated'by' the arrow'jin Fig: 2, thereby causinnr hook 21 to disen'gagey om pin 23.. Upon iscngagemcnt of Athe hook 21 'rom the pin' 23 the .blade 15 will bethrown out of engagement with the 'contact 16 by the spring 20.

The contr l mechanism 14 of the rheostat 3() com' rses'an arm 31 whichis pivotally' mounte on the base 11 at 32. The arm 31 is adapted to be movedover and to engage v The contacts 33 and the arm 31 are so connected, with the resistance in the rheostat, as to cause resistance to be cut out when the arm 31 is moved from one contact 33 to the next in the direction indicated by the arrow in Fig. 1. The end portion 34 of the arm 431 has a slot 35 in it,4 which causes a curved segment 36 to be-or'medpon the arm 31. On the 4top of the curved segment 36 there are ratchet' -teeth 37 which are adapted to be engaged by a awl 38 carried in a block or frame' 39,' sa1d frame being 191m' whish's attachee mounted around said:.segment. "lheyewl.-y

38 is pivotally mounted at 40 in the frame 45 tofjever arm 4 ofdlever 46. The 7ai' "48::ofthe lever 46 is Pshafed as slio'vli'ii'i 1,`nd is adaptredjto be noved ifn'the directi; n indicated bythe arrow when Electf-i'lfagii'et; is ,'nergic'ed.' f'. The lever 4eis;@wahrnehmen 50 one bmfcka .,512ehicli'ippunedn page iig. lcmmem'ifd the ever f`rx i 4.,L'tind the base 11 there, isV e fsiriiig 52 Q'v'vhih'tends t'o4 *keep the `jr'lflchal'iism ,jlst described in the 'position :sliovvii'in Figi. h' ,'Ihe"e is 'a'lpyr'o merl'4 53 in connection tilie ice'iifhich 'hasieed- Wires1154 eteHdngnto fthe finlacel 10,., The lntndj5'5 'ef-'iliepyhwfer 53 is'pive'fany mounreat Attechedft'o:tlieunclesde and attlieeiid o hiiidA 55 there is' a spring contact 57 which is adapted to.v pass over and engag'ehcon- -tacts 5S-gin the :traine of the pyro'rneter., The contattater 5,84 comprise plugs 59fthnt aremremovalglybeld or carried in socket 60,.4 There isa notch 59a in each: plug 59 vvhich allows the spring contact 57to paSs' 'over the plu s when vmovingfinone direction only. Tiie sockets 60 are all mounted on a .b'i'is-b'arl 61 which extends across the back of the Pyrometer.:.-Thebus-ba`r" (S1-is connected toma binding post G2 by means of a wire 63. Connected to the hand 55 at the pivotal mounting .S6-there is a wire 65 which connects the handand a binding post 66. It will be readily'seen that when the spring contact 5 7 engages onel of the contacts-58 a current ot' electricity can be passed from one binding post to the other. As the oven becomes heated the hond 55 of the -pyrometer will move in the direction indicated by the arrow inFig. 5and the spring contact 57 will engage the contacts 58 one after another. l

The pyrometcr 53 isconnected in a circuit :70 whichmay be energized by a battery 71. Relay I72 in the circuit V70 will operate every time the circuit 70 is complete, or every time the spring contact 57 engages one of the contacts 58. The actuation of relay 72 causes the ,completion of circuit 73 in which electro-magnet 49 is connected. The corn- 4p'letion of the circuit 73 causes euergiza'ti'on .ofthe electro-magnet ,49 =and thereby causes movement of lever arm 48 in the direction 4iiidictetlibyl' the-'arrow in Fig. 1. This -movement of lever arm 48 due to the connection of connecting rod 43 between the frame 39 and the lever arm 47 causes move- "f riietfof iframe 39inbthe direction indicated by the arrow in Fig. 1. The movement of frame 39 due tothe ment of pawl38 jwith 'one bftheif'tbhets Sgcas'efs'tnovement of arm 31. ,"'The' various fiirtsjo the mech'- anis'rn are' a'angedad proportioned as to 4cause"the movementfof arm 311:6 be' just suicient to hovei. from one lfcont-,'ct :33: to the Ielkt'I Whtithe 3.3131131 hasmoved from one contact 33 to the next a part ofthe r- 'istaiice 30 isctvout thereby allowing more 'to'maffe.entnommen-indicated b the arrowivin IFi 5 until itenggS-fanot er contact 58. hen the spring contuct-ghas engaged fanothisii 'contact 58 the-circuit 70 is agai'nfompleted and thelmechani'smmctuated so as tocause 'tleflever -rmBLfto move wehe den@certamenfrhe'rurnace continues to operte infthis manner until -the 'arm 55 engagesfod? The notches 59Jin the plugs' 59'f'nre"'so"asto allow contact '57 to pass over them in the 'directionrindicated w vnace be turtied'on. The' engagement of hand 55 with rod 75"'coznp`ltes 'u circuit 90 which is also gener ized by battery 71. 'The completion of circuit 9() causes 'actuation of` relay 91 which causes the closing ofcrcuit 92 in which is connected' electro magnet 2S. As has bcen'h'ereinbefore described, the 'energiz'ation'of electro-magnet 28 causes Inoveie'nt pf lever 24 and thereby releases hook 21 which allotvsthe switch 13 to be opened.

The ofjening-:o'th Switch 13 turns the furnace 10 oif and prevents it from becoming further heated.

It will `be vread-ily 'understood how the furu Vnace 4may be turned ofi at any desired temperature adjusting the rod 75. It is also possible to regulate the4 speed or rate at which the temperature 1of: the furnace will i increase. This regulation is accomplished byvaryifn the evenement of the Plugs 59 inL the Shoo ets 60j o instance, by spacing vthe plugs' 'as 4shov'vn"'in Fig'. 5,'the furnace 'will heat more slowly `Whereas if the pugs were placed in consecutive or adjacent sockets 60 the heating of the furnace will be more rapid. The arrangement of resistance is such that, upon any one actuation of rheostat arm 31 to throw out a resistance uni-t, the temperature of the oven will then gradually rise and in time rise suiliciently to carry pyrometer hand past several of the plug sockets and if the plugs are set a distance apart corresponding to the maximum distance the hand will travel after any one actuation of control arm 31, then the heating (the increase in temperature) will be of maximum slowness. By spacing the lugs 59 closer together tlie heating may correspondingly accelerated.

Having set forth a preferred form of the invention I do not wish to limit myself to the details hereinabove described but wish to 'reserve to myself any changes or modifications that may ap ear to those skilled in the art or that may all within the scope of the following claims.

Having described a preferred form of my invention, I claim:

1. In combination with an oven or the like, means for heating theoven to varying temperatures, and means for automatically finally discontinuinl the heating of said oven upon its readliing a predetermined filial temperature.

2. In combination with an electrically heated oven, temperature controlled means for varying the heating current, and temperature controlled means for finally completelly cutting oi such current.

3. n combination an electrically heated oven, temperature controlled means for varying the .heating current, said means ernbodying a movable contact arm and teni perature regulated electro-magnet means to move said contact arm, and temperature controlled means for entirely cutting off such current.

4. In combination, an electrically heated oven, temperature controlled means for varying the heating current, said means embodying a movable contact arm and temperature regulated electro-magnet means to move said contact, and temperature con trolled Imeans for entirely cutting off such current, said means embodying a pyrometer, and a switch adapted to be opened by said pyrometer.

'o'. In combination, an electrically heated oven, temperature controlled means for varying the heating current, said means embodying a movable contact arm, an electromagnet in an electric circuit adapted lto move said contact arm, and a pyrometer adapted to open and close said circuit.

6. In combination, an electrically heated oven, temperature controlled means for varying the hea-ting current, said means embodying a movable contact arm, an electromagnet in an electric circuit adapted to move said contact arm, and a pyrometer having a movable contact adapted to engage adjustable contacts and thereby open an close said circuit.

7. In combination, an electrically heated oven or the like, electric heating means therefor embodying a variable resistance, mechanical means for varying the resistance step by step, and actuating means for the mechanical means embodying a pyrometer actuated by the temperature of the oven, an actuating circuit including contacts adapted to be engaged by a moving part of the pyrometer, and a carrier for the contacts on which they may be adjustably arranged in spaced relation, either at distances equal to or less than the distance the moving part will move by reason of the variation of the resistance by one step.

8.A In combination with an oven or the like, means for hea-ting the oven to diil'erent temperatures, and temperature regulated electromagnetic means for controlling said heating means.

9. In combinatiomaii electrically heated oven or the like, electric heating means therefor embodying a variable resistance, mechanical means for varying the resistance step by step, actuating means for the mechanical means embodying a pyrometer actuated by the temperature of the oven, and means for automatically disconnecting finally the heating means upon the oven reaching a predetermined temperature, said means embodying an actuating circuit including an adjustable contact adapted to be engaged by a moving part of the pyrometer.

10. In combination with an oven or the like, heating means for the oven, means for energizing the heating means to cause the oven to successively reach certain predetermined higher temperatures after it has reached predetermined temperatures, and control means for the energizing means actuated by virtue of the oven reaching the predetermined higher temperatures.

11. In combination with an oven or the like, heating means for the oven adapted to heat the oven to certain predetermined temperatures after it reaches predetermined temperatures, temperature controlled means for controlling said heating imeans, said predetermined temperatures being successively one higher than the other, and means for automatically finally cutting ofi the heating means upon the oven reaching a predetermined temperature.

In witness that I claim the foregoing I have hereunto subscribed my name this 24th day of July, 1919.

ALFRED L. WILKES.

Witness VnioiNiA I. Baumann. 

